1. Technical Field
The present invention relates to an illuminated switch device in which a plurality of light sources are provided in a casing so as to correspond to a plurality of illuminated regions that are provided on an upper plate of an operating body, and more particularly, to a technique for preventing light leakage between different light sources.
2. Related Art
The structure of this type of illuminated switch device according to the related art will be described with reference to FIG. 7. In a casing 1, a first light source 3 and a second light source 4 are provided on a bottom plate member 2 so as to be parallel to each other, and a partition wall 5 is formed between the light sources 3 and 4. In addition, a switch element (not shown) is mounted on the bottom plate member 2, and external connection terminals (not shown) that are electrically connected to the switch element and the light sources 3 and 4 are provided at predetermined positions of the bottom plate member 2. An open end 1a is provided at the top of the casing 1. An operating body 6 is arranged so as to close the open end 1a, is supported by the casing 1 so as to be movable in the vertical direction, and is pressed. First and second illuminated regions 7 and 8 made of, for example, a light transmissive resin are provided on the upper plate 6a of the operating body 6. The first illuminated region 7 is opposite to the first light source 3, and the second illuminated region 8 is opposite to the second light source 4. A light-shielding wall 9 protrudes downward from the rear surface of the upper plate 6a of the operating body 6 to pass through the open end 1a. The light-shielding wall 9 is provided between a space below the first illuminated region 7 and a space below the second illuminated region 8. When the operating body 6 is moved in the vertical direction, the light-shielding wall 9 slides on the partition wall 5. A driving portion (not shown) that presses the switch element is attached to the operating body 6. When the operating body 6 is pressed, the driving portion is moved down together with the operating body to press the switch element. In this way, a contact switching operation of the switch element is performed. When pressing force against the operating body 6 is removed, the operating body 6 automatically returns to its initial position by elastic force of a return spring (not shown) (see JP-A-2006-252874).
In the illuminated switch device having the above-mentioned structure, when the first light source 3 is turned on, light is emitted to the first illuminated region 7 that is provided immediately above the light source. Therefore, it is possible to illuminate the first illuminated region 7. In this case, some of the light components emitted from the first light source 3 travel to the second illuminated region 8. However, since the partition wall 5 and the light-shielding wall 9 are formed of a light-shielding material, it is possible to prevent light emitted from the first light source 3 from leaking to the second illuminated region 8. Similarly, when the second light source 4 is turned on, light is emitted to the second illuminated region 8 that is provided immediately above the light source. Therefore, it is possible to illuminate the second illuminated region 8. However, light emitted from the second light source 4 to the first illuminated region 7 is shielded by the partition wall 5 and the light-shielding wall 9.
However, in the illuminated switch device according to the related art shown in FIG. 7, a clearance C for controlling friction between the light-shielding wall 9 and the partition wall 5 should be ensured. Therefore, there is a problem in that some of the light components emitted from the second light source 4 reach the first illuminated region 7 through the clearance C. That is, some of the light components emitted from the second light source 4 reach the first illuminated region 7 through the clearance C. When the first light source 3 is turned off, light should not be incident on the first illuminated region 7, but some of the light components emitted from the second light source 4 reach the first illuminated region 7 through the clearance C. In addition, when the first light source 3 is turned on, irregular brightness occurs in the first illuminated region 7 due to interference between light components emitted from the first and second light sources 3 and 4. As a result, it is difficult to obtain a good lighting quality.
In the structure shown in FIG. 7, in order to prevent light leakage between the light sources 3 and 4, the light-shielding wall 9 may be inserted between two partition walls formed on the bottom plate member 2, or the partition wall 5 may be provided between two light-shielding walls formed on the upper plate 6a. However, in this case, the diameter of the casing 1 or the operating body 6 increases, and the overall size of the switch device increases. Therefore, this structure is not preferable.